On the Oasis of the results obtained by IR, NMR and GC-MS analysis it is supposed that organic mtter of Khoot oil shale is a complex mixture of high molecular organic compounds mainly of naphthene-aliphatic character with long aliphatic chains connected with naphthene rings as well as with some substituents such as aromatic rings, carboxylic, carbonyl and hydroxyl groups. Such a structure is evidenced by obtaining aliphatic, naphthenic, aromatic and heterocyclic substances of different molecular mass by pyrolysis (decomposition) of the organic matter of oil shale.